An electrical device like this requires a reverse leakage current of 2.7μA @ 1V.While the device is operating, the maximum voltage - Zener (Nom) is reduced to 3.9V.For operation, diode reaches 1V @ 10mA at the maximum voltage - Forward (Vf).
BZT52C3V9S RRG Features
reverse leakage current of 2.7μA @ 1V 2.7μA @ 1V is the maximum voltage (Tol)
BZT52C3V9S RRG Applications
There are a lot of Taiwan Semiconductor Corporation BZT52C3V9S RRG applications of zener single diodes.